package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.SeckillVoucher;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.SimpleRedisLock;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.time.LocalDateTime;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 *  服务实现类
 */
@Service
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
    @Resource
    private ISeckillVoucherService seckillVoucherService;

    @Resource
    private RedisIdWorker redisIdWorker;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedissonClient redissonClient;

    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();
    @PostConstruct
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    private class VoucherOrderHandler implements Runnable{
        String queueName = "stream.orders";
        @Override
        public void run() {
            while (true){
                try {
                    //1、获取消息队列中的订单信息  XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS stream.order >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );

                    //2、判断消息获取是否成功
                    if (list ==null || list.isEmpty()){
                        //2.1、如果获取失败，说明没有消息，继续下一次循环
                        continue;
                    }
                    //3、解析消息中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);

                    //4、如果获取成功，可以下单
                    handleVoucherOrder(voucherOrder);

                    //5、ACK确认  SACK stream.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName,"g1",record.getId());

                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    handlePendingList();  //异常处理
                }
            }
        }
        private void handlePendingList() {
            while (true){
                try {
                    //1、获取PendingList中的订单信息  XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS stream.order 0
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );

                    //2、判断消息获取是否成功
                    if (list ==null || list.isEmpty()){
                        //2.1、如果获取失败，说明PendingList没有消息，结束循环
                        break;
                    }
                    //3、解析消息中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);

                    //4、如果获取成功，可以下单
                    handleVoucherOrder(voucherOrder);

                    //5、ACK确认  SACK stream.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName,"g1",record.getId());

                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    try {
                        Thread.sleep(20); //休眠
                    } catch (InterruptedException ex) {
                        throw new RuntimeException(ex);
                    }
                }
            }
        }
    }



    /*private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);
    private class VoucherOrderHandler implements Runnable{
        @Override
        public void run() {
            while (true){
                try {
                    //1、获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    //2、创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                }
            }
        }
    }*/

    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        //1、获取用户
        Long userId = voucherOrder.getUserId();
        //2、创建锁对象
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        //3、获取锁
        boolean isLock = lock.tryLock();
        //3、判断是否获取到锁
        if (!isLock) {
            //获取锁失败，返回失败
            log.error("不允许重复下单");
        }
        try {
             proxy.createVoucherOrder(voucherOrder);
        } finally {
            //释放锁
            lock.unlock();
        }
    }

    private IVoucherOrderService proxy;

    /**
     * 实现秒杀下单
     * @param voucherId
     * @return
     */
    @Override
    public Result seckillVoucher(Long voucherId) {
        //获取用户
        Long userId= UserHolder.getUser().getId();
        //获取订单id
        long orderId = redisIdWorker.nextId("order");
        //1、执行lua脚本
        Long result = stringRedisTemplate.execute(SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                userId.toString(),
                String.valueOf(orderId)
        );

        //2、判断结果是否为0
        int r = result.intValue();
        if (r != 0) {
            //2.1、不为0，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }

        //3、获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();

        //4、返回订单id
        return  Result.ok(orderId);

    }

    /*@Override
    public Result seckillVoucher(Long voucherId) {
        //获取用户
        Long userId= UserHolder.getUser().getId();
        //1、执行lua脚本
        Long result = stringRedisTemplate.execute(SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                userId.toString());

        //2、判断结果是否为0
        int r = result.intValue();
        if (r != 0) {
            //2.1、不为0，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        //2.2、为0，代表可以购买，把下单信息保存到阻塞队列
        VoucherOrder voucherOrder = new VoucherOrder();
        //2.3、订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //2.4、用户id
        voucherOrder.setUserId(userId);
        //2.5、代金券id
        voucherOrder.setVoucherId(voucherId);
        //2.6、创建阻塞队列
        orderTasks.add(voucherOrder);

        //3、获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();

        //4、返回订单id
        return  Result.ok(orderId);

    }*/

    /*@Override
    public Result seckillVoucher(Long voucherId) {
        //1、查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);

        //2、判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            //秒杀未开始
            return Result.fail("秒杀未开始");
        }

        //3、判断秒杀是否结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            //秒杀已结束
            return Result.fail("秒杀已结束");
        }

        //4、判断库存是否足够
        if (voucher.getStock() < 1) {
            //库存不足
            return Result.fail("库存不足");
        }

        Long userId = UserHolder.getUser().getId();
        //创建锁对象
        //SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        //获取锁
        boolean isLock = lock.tryLock();
        //判断是否获取到锁
        if (!isLock) {
            //获取锁失败，返回失败
            return Result.fail("一人一单，不允许重复下单");
        }
        try {
            //获取代理对象（事务）
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        } finally {
            //释放锁
            lock.unlock();
        }

    }*/

    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        //5、一人一单限制
        Long userId = voucherOrder.getUserId();
        Long voucherId = voucherOrder.getVoucherId();
        //5.1、查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
        //5.2、判断是否存在
        if (count > 0) {
            //用户已经下单了，不能再下了
            log.error("每人限购一张");
        }

        //6、扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")
                .eq("voucher_id", voucherId)
                .gt("stock", 0) //where id =? and stock > 0 乐观锁实现秒杀优惠券超卖问题
                .update();
        if (!success) {
            //扣减库存失败
            log.error("库存不足");
        }

        //7、订单写入数据库
        save(voucherOrder);
    }
}
